A LITTLE over a decade ago, when JinkoSolar, a Shanghai-based company, entered the solar business, it was such a novice that when it visited international trade fairs, all it had was a bare table and a board with its name scribbled on it. But it also had luck, a technological edge and lots of public money on its side.

The industry globally was riding high on subsidies. Generous feed-in-tariffs (FITs), financial incentives for installing solar, made Germany the world’s largest solar market by around 2010. Germans turned to China for cheap sources of crystalline silicon solar panels, not least because subsidised land and loans enabled China’s fledgling manufacturers to undercut European and American competitors.

When European solar subsidies slumped during the euro crisis, the Chinese government once again stepped in to support its renewable-energy champions. It offered FITs to slather the remote west of China with solar farms. By 2013 China had eclipsed Germany as the world’s...